Classifications

Question 1

What is systematics?

Answer 1

It’s a system used to classify & name organisms.

Question 2

What is systematics based on?

Answer 2

● Based on phylogenetic trees.

● Based on shared derived characters.

Question 3

Phylogeny/Tree Terminology

What are nodes & zen nodes?

Answer 3

● Nodes = common ancestors/ speciation events.

● Zen nodes = unique ancestor.

Question 4

What are monophyletic groups?

Answer 4

They are groups that share a recent common ancestor.

ANCESTOR + ALL DESCENDANTS

Question 5

What are paraphyletic groups?

Answer 5

They are groups that don’t include all descendants of the common ancestor.

ANCESTOR + SOME DESCENDANTS

eg_ Reptilia.

Question 6

What are polyphyletic groups?

Answer 6

They are groups with members that don’t all belong to one most recent common ancestor.

> 1 ANCESTOR

Question 7

Name & define the 8 characters [CA³S²HP]

Answer 7

● Convergent characters
= characters that arise independently in unrelated groups.

● Apomorphy
= derived characters.

● Autapomorphy
= a specialized character that is unique to a monophyletic group.

● Analogous characters
= characters that tend to mislead one into assuming close relatedness but have no relation at all.

● Synapomorphy
= shared derived characters within a group.

● Symplesiomorphy
= shared ancestral characters within a group.

● Homologous characters
= characters in different organisms that relate these organisms due to common ancestry.

● Plesiomorphy
= individuals share an ancestral character.

Question 8

What are the evolutionary trends observed in floral form of plants? (6)

Answer 8

● Many - Few (flowers).
● Superior - Inferior (ovary position).
● Free - Whorled (whorl parts).
● Radial - Bilateral (floral symmetry).
● Bisexual - Unisexual (flower sexuality).
● Parietal - Axial - Central (placentation).

Question 9

Examples of evolutionary trends plants? (2)

Answer 9

● Archaefructus
= earliest angiosperms.

● Amborella
= earliest extant angiosperms.